Method and apparatus for producing an even continuous layer of fibers

ABSTRACT

The fiber arrangement removed from the feed chute is monitored down stream of the chute to detect deviations in thickness or mass of the fiber arrangement from a preset value so that the deviations are used to cause an increase or decrease of the pneumatic pressure acting on the top of the fiber flock column. The change in pressure results in a change in the amount of pressure drop to which the column is subjected so that the degree of condensation of the column is likewise changed to eliminate or reduce further deviations.

United States Patent [191 Binder et al.

[ 51 Jan. 9, 1973 [54] METHOD AND APPARATUS FOR PRODUCING AN EVENCONTINUOUS LAYER OF FIBERS [75] Inventors: Rolf Binder, Raterschen;Christof Grundler; Rudolf Wildboltz, both of Winterthur, all ofSwitzerland [73] Assignee: Rieter Machine Works, Ltd., Winterthur,Switzerland [22] Filed: Oct. 14, 1970 [21] Appl. No.: 80,656

[52] US. Cl ..222/55, 19/105 CF, 19/240 [51] Int. Cl. ..DOIg 15/40 [58]Field of Search ..l9/l05 CF, 240; 222/55;

[56] References Cited UNITED STATES PATENTS 3,4l4,330 l2/l968Triitzschler ..l9/l05CF 3,562,866 2/l97l Roberson et. al. 19/2403,552,800 1/1971 Triitzsehler ...l9/l05 CF 3,536,002 10/1970 Miller..222/55 X Primary Examiner-Robert B. Reeves Assistant ExaminerThomas E.Kocovsky Attorney-Kenyon & Kenyon Reilly Carrer & Chapin [57] ABSTRACTThe fiber arrangement removed from the feed chute is monitored downstream of the chute to detect deviations in thickness or mass of thefiber arrangement from a preset value so that the deviations are used tocause an increase or decrease of the pneumatic pressure acting on thetop of the fiber flock column. The change in pressure results in achange in the amount of pressure drop to which the column is subjectedso that the degree of condensation of the column is likewise changed toeliminate or reduce further deviations.

22 Claims, 13 Drawing Figures PATENTEDJAI 9mm 3.709.406

SHEET 1 BF 5 INVENTORS ROLF BINDER I CHRISTOF GRUNDLER BY RUDOLFWILDBOLZ %?Witiii2 PATENTED JAN 9 I973 SHEET 2 OF 5 Fig.7

PATENTEDJAN ems I 3.709.406

saw u or 5 INVENTORS Rom- Smog? grin/STOP GR B RuooLF WILDBOLZPATENTEUJM! ems 3.709.406

SHEET 5 [IF 5 INVENTORS QOLF Emogn CHRISTOF QQ NDI- R BY RUQOLF WmoaoLzMETHOD AND APPARATUS FOR PRODUCING AN EVEN CONTINUOUS LAYER OF FIBERSThis invention relates to a method and apparatus for producing fiberstrands and, more particularly, for producing an even continuousarrangement of fibers from a continuous stream ofindividualized fiberflocks.

It has been known in the preparation of staple fiber for spinning toopen fiber flocks into small sizes by means of a beater, to transfer theopened flocks directly into a feed chute provided at a card without theformation of laps for condensing of the fiber within the feed chute andto discharge the same as a bat. In this way, a functional unit has beenformed between the beater and card. However, it has been found that inthe transport of the loose fiber material within this functional unitvariations of flow have occurred such that a certain degree ofirregularity in density of the chute output material has occurred. Theseirregularities have then been transmitted into the web taken from thecard as well as into the sliver formed from the web. This results in adisadvantage in subsequent processing steps.

In order to prevent too high a degree of irregularity in the chuteoutput, costly additional processing steps or the use of more complexprocessing equipment have been required.

It has also been known to connect a plurality of feed chutes to apneumatic flock transporting duct wherein the duct has been closed atone end and the arrange ment has been provided with a feed devicecontrolled according to the filling level of the feed chutes. The chuteshave also been provided with vertical slots through which the air streamhas been separated from the flocks and which have been increasinglycovered with flocks until being finally entirely covered as the flocklevel in the chute has mounted. In this arrangement, the pressure in thechutes and in the transporting duct reaches a maximum at which time, thesupply is stopped until the pressure is reduced sufficiently as theslots are uncovered owing to the decrease in the level of the materialin the chutes. In order to maintain sufficient material levels in thechutes, the material must be supplied with a small surplus. Thus, theduct has been supplied with flock material intermittently with a resultthat the pressure has constantly varied between a maximum and minimum.This has, however, resulted in variations of the flock material densitydepending directly on the pressure drop acting on the material in thechute.

The same results have also been obtained where the flock material, afterbeing deposited in a first chute, has been transferred after passingthrough a beater into a second chute arranged below the first andcondensed in the second chute by means of intermittent impulses ofcompressed air generated at a certain frequency and pressed through theflock material column. In this case, the material supply to the lowerchute has been controlled by a pressure control switch (manometer-relay)which has interrupted the supply if a pressure corresponding to acertain material level is reached and thereafter has initiated thesupply when the pressure drops to a lower value due to the decrease ofthe material level. Since the average pressure to which the flockmaterial column has been subjected varies between two extreme values,corresponding variations of fiber material density in the chute and inthe fiber layers taken from the chute have necessarily occurred.

In cases such as the above, it has been proposed to transfer and doublethe slivers produced on a group of cards into a drawframe, to deliverthe sliver from the drawframe into cans and to weight the sliver uponcompletion of the filling of a can. In a known arrangement, in order toreduce any irregularities in the delivered sliver, the set value of theauto-evening drawframe has been adjusted according to the weightdeviations of a sliver filled can from a set weight. In another knownarrangement, the set values of all pressure control switches provided inthe lower chutes have been correspondingly adjusted by means of aservo-motor. These techniques, however, have a further and decisivedisadvantage in that the time lag between the measurement of the weightof a full can and the point of adjustment has been very long, i.e., onlyvery long term variations over a period of hours can be evened out. As aresult, since the general rule in control technology is that onlyfluctuations having a duration which exceeds the control time lag by 4to 5 times can be levelled out without the danger of the control systembecoming in stable, and since normal can filling time is presentlyapproximately 30 minutes, only fluctuation periods exceeding 2 hours canbe controlled. A large part of the fluctuations caused by the openingequipment, however, has been of shorter duration and thus cannot belevelled out.

Accordingly, it is an object of the invention to eliminate variations inthe condensation of a flock material column deposited in a feed chute sothat a very even output at the delivery end of the chute can beobtained.

It is another object of the invention to prevent the occurrence ofvariations in loose fiber material deposited into and processed througha chute in a spinning installation.

It is another object of the invention to avoid irregularities in theoutput of a chute in a fiber processing apparatus.

It is another'object of the invention to effect an even output from asingle chute as well as a plurality of feed chutes supplied from acommon transporting duct.

It is another object of the invention to level out variations in thedensity of a delivered fiber material in a plurality of feed chutesconnected to a common transporting duct.

It is another object of the invention to control pressure conditions inthe chutes without any influence by the flock material column level tothus eliminate deviations in the flock material column density resultingfrom such influences.

It is another object of the invention to not only eliminateirregularities originating in the transporting duct between the beatingpoint and the feed chutes and during the separation, but also toeliminate a major part of the long term variations in the fiber materialsupply originating from the opening processes down to a duration offluctuation of several minutes only, so that in most cases all furtherlevelling in drafting processes with the continuous sliver of fibers,e.g., with the card sliver can be eliminated.

It is another object of the invention to level out flock layer weightvariations while avoiding oscillations of the control system.

It is another object of the invention to obtain conditions for optimumsetting off a control system for pressurizing flock material columns.

It is another object of the invention to be able to avoid variations inan escape cross-sectional area for a transporting air through a chutewall while eliminating flock column level variations.

It is another object of the invention to avoid any need to vary thespeed of the withdrawal rollers of a chute in order to adjust thedensity of the fiber arrangement withdrawn from the chute.

Briefly, the invention provides a method and apparatus of producing aneven continuous arrangement of fibers from a continuous stream ofindividualized fiber flocks.

In accordance with the method, a fiber flock column is formed in a feedchute by depositing at least a portion of the fibers of the continuousstream into the chute. While the upper end of the column is subjected tothe pressure in the duct, the lower end of the column is subjected to alower pressure so that a pressure drop is created longitudinally throughthe fiber flock column. The pressure drop thus serves to condense, orcompress, the fiber material in the column. In addition, the fibermaterial is removed from the chute in' a suitable arrangement such as afiber layer and its monitored for deviations in thickness or othercharacteristics of the mass of the fiber layer from a preset value. Thedeviations are then used to vary the pressure drop in the chute so as tochange the degree of condensation of the fiber flock column in order toeliminate subsequent deviations.

In one embodiment, the measurements of the fiber layer delivered fromthe feed chute are taken near the end of the chute as the fiber layer isdelivered. In other embodiments, the measurements are taken e.g. at thetake-in roll or the delivery end ofa card associated with the feedchute, or on either side of a drawframe connected to a plurality ofcards connected with a similar plurality of feed chutes connected incommon to a transporting duct. In these various cases, the time lagbetween when the measurements are taken and when a correction in thepressure drop are brought about varies from an optimum minimum to aslightly higher minimum.

In still another embodiment, the level of the fiber block column ismaintained at a constant level while the measurements are taken.

In accordance with the invention the apparatus includes a pressurizedtransporting duct from which one or more feed chutes depend. Each feedchute is constructed to form a fiber flock column therein and to createa pressure drop longitudinally of the column so that the pressure dropserves to condense the fiber material in the column. Suitable means arealso provided to remove the fiber material from each chute in a fiberarrangement e.g., a layer for delivery to a machine such as a card. Inaddition, a measuring device is provided for measuring deviations of thethickness or density of the fiber arrangement from a preset value and isconnected with a pressure varying means which creates the pressure inthe transporting duct in order to control the operation of this meansfor changing the degree of pressure drop in the chute.

In one embodiment, the means for creating the pressure in thetransporting duct is a fan, the rotation of which is varied inaccordance with the sense of the deviation in the fiber arrangement. Inanother embodiment, this means is in the form of a baffle which ismovably mounted in the duct downstream of the chutes for changing thecross-sectional flow area of the duct and thus the pressure.

In those instances where a chute can be supplied with flocks in amanner, as is known, (compare U.S. Pat. No. 3,400,518) so that no feedback of flocks occurs and wherein the whole flock carrying transportingair stream escapes via a perforated wall of the chute, changes in airpressure, and thus deviations of the weight of the fiber arrangementwhich are caused by variations of the flock level which are unavoidablein this type of chute, can be levelled out by the proposed controlsystem to a degree which in many cases is entirely sufficient. Thecontrol power ofthis embodiment, however, is limited due to thenon-ideal control characteristics. This, however, can be overcome bykeeping the free escape cross-section area constant.

An apparatus for implementing this latter embodiment includes a chutewhich is provided with a perforated zone for draining the transportingair and a flock column level control device in the region of theperforated zone which controls the quantity of fiber flocks to besupplied in order to maintain the flock column level.

The expression fiber layer used herein describes a continuous fiberarrangement composed of fiber comprising the fiber material as deliveredby feed chutes as well as slivers as delivered by a card or a drawframe.

These and other objects and advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in conjunction with the accompanying drawings in which:

FIG. I illustrates a side view of a plant for pneumatically supplyingfeed chutes for depositing flocks in a carding room;

FIG. 2 illustrates a plan view of the plant of FIG. 1;

FIG. 3 illustrates a side view of another plant for pneumaticallysupplying feed chutes for depositing flocks in a carding room;

FIG. 4 illustrates a plan view of the plant of FIG. 3;

FIG. 5 illustrates a cross-sectional view of a flock feeder according tothe invention;

FIG. 6 schematically illustrates a control system for controlling theair pressure within a feed chute according to the invention;

FIG. 7 schematically illustrates a control system associated with aplurality of cards according to the invention;

FIG. 8 schematically illustrates a control system in accordance with theinvention for measuring a sliver delivered by a card;

FIG. 9 schematically illustrates a control system according to theinvention for measuring a plurality of slivers on a drawframe;

FIG. l0 schematically illustrates a control system of the inventionutilizing a baffle in the transporting duct;

FIG. II schematically illustrates a control system according to theinvention wherein a baffle in a transporting duct is moved in accordancewith the passage of a plurality of slivers through a funnel;

FIG. 12 illustrates a modified control system for controlling a motorfor a fan in the transporting duct according to the invention; and

FIG. 13 schematically illustrates another control system according tothe invention for controlling the air pressure within a singleperforated feed chute.

Referring to FIGS. 1 and 2, a fiber processing plant includes a supplyduct 1 which supplies fiber material e.g. pneumatically by means of atransporting air stream from a suitable opening and cleaning apparatus(not shown) located upstream of the duct 1 to a flock feeder 2.

Referring to FIG. 5, the flock feeder 2, in turn, has a condenser 3mounted therein which serves to separate the fiber material from thetransporting air stream by means of a perforated drum (not shown) and todeposit the separated fiber material into a reserve chute 4 (FIG. 5). Afeed roll 5 and pedal levers 6 are mounted to form a nip below the chute4 so as to transfer the fiber material to a beater 7, e.g.,Kirschner-Beater, which opens the fiber material into fine flocks. Atransporting fan 8 connects via an inlet opening 18 to a room, orchamber, 9 surrounding the beater 7. This fan 8 serves to draw in theflocks and the transporting air stream from the surrounding room and totransfer the flocks and air stream in the form of a continuous flockstream into a transporting duct 11 arranged above and connected incommon to a plurality of vertical chutes 10.

Referring to FIG. 6, each chute 10 is connected with the transportingduct 11 via a separator head 12 by means of which the flocks aredeflected from the flock stream into the chute 10. During operation, thesupply of flocks continues until the fiber flock column deposited in thechute 10 builds up to the level of the separator head 12 thus reaching aheight h. In addition, a pair of takeoff rolls 13, 14 is arranged with aclearance 15 below the lower end of each chute 10 such that the lowerend of the chute 10 is not hermetically sealed from the surroundingroom. During operation, a pressure p, exists in the transporting duct 11while a lower pressure p exists in the surrounding room. As a result, apressure drop or differential Ap= p p, develops in the transportingmedium between the lower chute end and the upper level h of the flockcolumn so that the column is compressed, i.e., condensed, under theinfluence of the pressure drop Ap. In this manner, all the chutes 10filled with fiber material are influenced by this pressure drop Ap.

Referring again to FIG. 5, the transporting air, as far as it has notleaked via the small clearance 15 at the lower chute ends, returns intoa feed back chute 16 of the flock feeder 2 carrying excessive flockmaterial therewith. In addition, an air duct 17, the inlet ofwhich issuitably arranged, again exhausts the transporting air into the room 9from which the air is taken into the inlet opening 18 of the fan 8 whilethe flocks remain in the feed back chute 16. A plurality of continuouslydriven metering rolls 19 are used to transfer the flocks in the chute 16via the beater 7 without passing, how ever, through any nip, back intothe inlet opening 18 and thus into the transporting air circuit.

Referring to FIGS. 1 and 2, the fiber layer 20 delivered from the chutes10 by the takeoff rolls 13, 14 is in a compacted state and istransferred into a card 21 to which a chute 10 is connected. Each card21 produces a sliver 22 which is deposited into a can 23 as is known.

. Referring to FIGS. 3 and 4, wherein like reference characters indicatelike parts as above, the cards 21 can alternatively deposit the sliver,e.g., via a sliver reserve box (not shown) onto a sliver transportingdevice such as a transporting belt 24 extending along a row of cards 21.The slivers 22 can then be placed successively sideby-side onto the belt24 and supplied jointly to a drawframe 25.

Referring to FIG. 6 in either of the above cases, as the pressure drop Ap acting on the fiber flock column increases, the condensation of thefiber flock columns in the chutes 10 becomes more intense. As a result,this relation can be checked by monitoring the thickness of the fiberlayer 20 delivered at the lower end of the chute 10 by the take-offrolls 13, 14. To this end, one of the supporting rolls 14 is movablysupported under a spring pressure and is connected by a suitable meansto a measuring device 26 so that the movements of the supporting roll 14during changes in thickness of the layer 20 passing from the nip betweenthe rolls 13, 14 can be detected and measured. The measuring device 26which can be of any suitable structure is also used to emit anelectrical signal proportional to the roll deviation from a presetposition to a control device 27. The control device 27, in turn, isconnected to the motor 28 of the fan 8 (FIG. 5) so as to vary the speedof the fan 8 in response to the signal received from the measuringdevice 26. The control device 27, thus functions as a correcting elementof the control loop to adapt the pressure p to a required value untilthe deviation of the measured fiber layer thickness from the presetthickness value has vanished. In this regard, the control device 27 canbe of any suitable commercially available device in which a proportionalcharacteristic, or an integral characteristic, or if desired, a PIDcharacteristic can be set.

Depending on whether the measuring device 26 detects and measures adecrease or increase in the thickness of the layer 20, the press'urep inthe transporting duct 11 is varied so that subsequent condensation ofthe flock column in the chute 10 is thus cor respondingly increased ordecreased. In this manner, weight variations in the fiber layer 20 arelevelled out practically without any time lag, as such variations aremeasured at the earliest moment possible, i.e., as the fiber layer 20leaves the chute I10, and as the flock column reacts to the increase inpressure in the transporting duct 11 with an increased condensing effectdown to the lowest portion thereof without any delay. In this respect,the flock column behaves like a spring with non-linear characteristicswhich is compressed under pressure, i.e., thc flock column is compressedproportionally in its lowest portion immediately above the take-offrolls, not considering the influences of friction against the chutewalls and of gravity. The system thus functions with a neglegible timelag.

If a plurality of feed chutes 10 are connected to a common transportingduct 11, it is entirely sufficient to control the fan speed according tothe measurements taken at one single chute 10 only and thus to controlflock condensation jointly in all flock columns. A most simple centralcontrol can therefore be obtained. Furthermore, one measuring deviceeach can be provided at two or three feed chutes connected to a commontransporting duct with the signals of each measuring device beingalternatingly transmitted to the control device 27. In this way, if themeasuring device connected to the control device happens to be locatedat a chute which is out of operation at a given time, the connection canbe switched over to another measuring device located at an operatingchute.

Referring to FIG. 7, a further alternative consists in the arrangementof a measuring device 26', 26", 26", 26" at each card (not shown) eitherupstream or downstream thereof for measuring the thickness of sliverproduced with the devices being connected to a common control device 29which establishes the arithmetic means of the signals received from themeasuring devices 26-26" and then influences a correcting member 30,which can be the fan 8 as described above, or a throttling baffle asdescribed below (FIG. 10) in dependence on the arithmetic mean.

Referring to FIG. 6, the measurement of the fiber layer 20 also can beeffected by means of a measuring device 31 located at a feed roll 32 forthe taker-in 33 (licker-in) of the card 21 if a time lag of one to twominutes for transporting the material from the takeoff rolls l3, 14 tothe feed roll 32 can be tolerated as a reaction time lag of the controlloop. The measurement obtained in the device 31 is then used in similarfashion as above to control the speed ofa fan motor as above or athrottling baffle as below.

Referring to FIG. 8, a measuring device 35 can alternatively be providedto measure the thickness of the sliver 22 delivered from the cards 21 asthe sliver enters the nip of a pair of calender rolls 34. Themeasurements obtained are then used as above to produce a signal whichis processed further to effect the pressure p in the transporting duct11. In this case, since the throughput time of the card is within a fewseconds, the reaction time lag, as compared to the arrangement in whichthe measuring device is provided at the feed roll 32, is onlyinsignificantly increased.

Where the cards are to deliver the sliver into cans as shown in FIGS. 1and 2, the methods and measuring devices described above are to be used.However, where the cards deliver the sliver onto a common slivertransporting arrangement e.g., as shown in FIGS. 3 and 4, additionalmethods and measuring devices as described below can be used.

Referring to FIG. 9, a measuring device 36 is located on the drawframe25 supplied with slivers 22 by the common sliver transportingarrangement 24 in order to measure the thickness or density of thesliver 22. In this case the reaction time lag is increased byapproximately to seconds, the advantage, however, is that a summarizedmeasuring value of the slivers 22 is obtained rather than individualmeasuring values.

Referring to FIG. 10, instead of varying the speed of the fan 8 (FIGS. 1and 3) to vary the pressure p in the transporting duct 11, a baffle 38is provided in the duct section between the last chute I0 and the flockfeeder 2 and is controlled via a control device 37 to narrow or enlargethe effective duct cross-section area of the duct I and thus change thepressure p prevailing in the duct 1. The control device 37 is actuatedin any of the manners described above in dependence on the fiber layeror sliver thickness or mass.

Referring to FIG. 11, instead of measuring the thickness of the fibermaterial, another characteristic of the density or mass of the fibermaterial can be measured. To this end, in order to measure the fibermass of a plurality of slivers 22, a measuring funnel 39 is interposedin the path of the slivers 22 so that the slivers 22 are broughttogether in passing through the funnel 39. In addition, a duct 40 isconnected to communicate with the interior of the funnel 39 so as tohave a signal pressure p, produced within the duct 40. This signalpressure p, depends on the fiber mass passed through the funnel 39. Theduct 40 is further connected to a pneumatic control device 41, e.g., viaa dampening element 42 so that the signal pressure p, can be transmittedthereto. The control device 4] serves to generate a control pressurewhich is emitted at an output 43 and transferred via a throttling valve44 and dampening element 45 to a piston 46 in order to move the piston46. The piston 46 is, in turn, connected to a baffle 47 located within atransporting duct 11 so that the piston movements are transferred to thebaffle 47. In this way, the movements of the baffle 47 serve to vary thecross-sectional flow area of the duct 11 and thus the pressure p,.

Alternatively, referring to FIG. 12, the movements of the piston 46 canbe used to adjust the position of the brushes 48 of a commutator motor49 of a fan (8 as shown in FIGS. 1 and 3) to vary the pressure p,.

As a further alternative, the control of the pressure p, can be effectedintermittently by means of a two-point level switch. In this case, thecorrection would start only when a predetermined deviation from a setvalue is measured.

Referring to FIG. 13, a flock feeder 51 having a feed chute 52 issupplied with fiber material from a source such as an opening machine(not shown) while a takein roll 53 transfers the material via a trough54 to a beater 55, which opens the material into fine flocks. A suctionnozzle 56 ofa material transporting fan 57 is in communication with thebeater to transport the material into a chute 58 arranged on thepressurized side of the fan 57. The chute 58 includes a perforated wall59 which opens to an exhaust duct 60 so that the flock carrying airstream can escape into the duct 60 while the flocks are retained by theair stream on the inside of the wall 59 due to an appropriate small sizeof the perforations. The flocks are thus deposited in the form ofa flockcolumn 61.

During operation, a pressure p prevails in the exhaust duct 60 while alower pressure p is maintained by the fan 57 above the flock column. Apressure drop A p thus occurs to bring about a condensing of the column.The flock column thus formed is additionally condensed by a pair oftake-off rolls 62, 63 and is transferred in the form of a fiber layer 64to a machine for taking in the fiber layer 64, e.g., to a card 65.

The left hand roll 62 of the take-off rolls 62, 63 is mounted in abearing 66 and together therewith pivots around a pivoting point 67 andis pressed against the roll 63 by a weight 68. The bearing 66 alsosupports a conical pin 69 which penetrates into a bore 70 of a member 71through which air flows. The pin 69 is mounted and sized so that themiddle position of the pin 69 corresponds e.g., to the set value of thefiber layer weight. The members 69, 70 and 71 thus form a pneumaticsignal transmitter which acts on a control mechanism 72 in order totransmit a signal thereto corresponding to the air flow through themember 71. A set value transmitter 73 is also connected to the controlmechanism 72 to transmit a preset signal thereto. A signal proportionalto the mass deviation is obtained in the control mechanism 72 when adeviation occurs and is transferred to an amplifier 74, the pneumaticoutput signal of which directly displaces a piston 75. The piston 75, inturn, is connected to the motor 76 of the fan 57 to change therotational speed of the motor 76 and thus change the pressure p in thechute 58. A suitable means 83 is also provided to supply air via a line84 to the various components 71-74 for use in the operation of thesecomponents.

The condition for optimum action of this control system is theelimination of influences which could result in control deficiencies,such as e.g., elimination of clogging of the perforations in the wall 59by choosing suitable shapes for the perforations, e.g., narrow verticalslots and/or suitable materials on which fibers are not caught.Furthermore, care should be taken that the pressure p is not subject toexcessively large varia tions.

It is of particular importance, however, for good controlcharacteristics that the air throughput zone L pro vided in theperforated wall 59 above the flock column h, which zone actually is athrottle point in the air stream, is maintained constant. This isachieved by maintaining the height h of the flock column constant, forexample, very simply bymeans of a photocell ar rangement 77 and a relay78 arranged at the desired height h. The relay 78 switches the take-inroll 53 off as the light beam of the photo cell arrangement 77 isinterrupted and switches the take-in roll 53 on as a photo current againreaches the relay 78. If the chute 58 is of a certain minimum height, atime delay in the on and off switching can be used to reduce theswitching frequency, without causing excessive deviations of the airescape height to the flock column height from the value desired. Anotheralternative construction consists in reducing or increasing therotational speed of the take-in roll 53 so that the desired height h ofthe flock column is maintained constant at all times.

in order to provide for a limiting range of control movements, thepiston rod 79 of the piston 75 is provided with a cam 80 which serves toactivate a pair of limit switches 81 and 82 each of which is disposed atthe outermost positions of the piston 75. These limit switches areactivated as the limits of the control range are reached, which may bethe case if disturbances of the material supply or lap-ups on the rolls62 and 63 occur. The limit switches 81, 82 can also be used for activating an acoustical or optical alarm system or for stopping thematerial transport upstream and downstream from the chute.

This latter arrangement presents a number of advantages insofar as it issuitable for a high-production individual chute feed without materialfeed back wherein a pressure drop control satisfying all therequirements presently demanded can be obtained in simple manner. It isa further advantage that a normal suction duct only is required to theflock supplying machine since the pressure generating device can bepositioned in the upper part ofthe chute. This arrangement permitshandling of large quantities of air and flocks such as more than 50 kgper hour as needed for feeding ultra high production cards or othermachines of high production rates processing fiber layers.

It is to be noted that in the case of a high material throughput in themachine connected to the feed chute, in an extreme case, a feed chute 10as shown in FIG. 6 can be fed directly by a flock feeder 2 with the duct11 feeding directly back into the flock feeder 2. This system thenconsists, as a whole, apart from the flock feeder and the transportingduct 11, of only one chute.

it is also noted that if a plurality of chutes 10 are arranged in thefeeding and backfeeding portions of the transporting duct ll, a centralpressure control can be effected using a single guide chute equippedwith a measuring device. In this case, a measuring device is associatedwith only one of a number of guide chutes connected to a common airtransporting duct and is connected to a pressure generating device inthe air transporting duct. Should the fiber arrangement from the chutevary, the measuring device detects the variation and adjusts thepressure generating device to eliminate subsequent variations. Thus,there is no need to change the speed of the withdrawing rollers at thevarious chutes. As a result, not only is there no need for rotationalspeed control devices for the withdrawal rollers at the various chutesbut also there is no need for measuring devices at the other chutes.This, results in a considerable savings. The invention thus enables aden sity control in a plurality of chutes without being forced to resortto speed variation devices at the chutes and the cards which wouldinvolve considerable changes in the driving arrangements of thewithdrawing rollers of the chutes with respect to those of the cards.

The invention thus provides a means by which reaction time lag canpractically be eliminated by arranging the measuring device at thetake-off rolls of the chute so that the control system reacts veryquickly. Further, if the measuring device is arranged at. the carddelivery, the reaction time lag achieved is still sufficiently smallconsidering the card production rates presently used so that a majorpart of the variations originating in the opening and cleaning equipmentcan be eliminated.

The use of the invention in a card feeding system presents a number ofparticular advantages which are enumerated in the following.

In an arrangement using a fan or an adjustable throttling baffle as acorrecting element of the control loop, no factor connected with thematerial supply to the transporting duct is varied, i.e., no speeds offeeding element must be varied. Instead, control is achieved by means ofthe transporting medium itself, the transporting means ofwhich must beprovided in any case.

Under certain conditions, in the case of a sliver transportingarrangement with an auto-levelling drawframe, which is used to level outshort term as well as long term variations, the invention allowsreplacement of the auto-levelling drawframe by a simple drawframe whichcompensates for sliver breakage only, i.e., which corrects the drawingratio by means of a simple speed change gear. If, however, theauto-levelling drawframe should not be dispensed with due to itslevelling of the short term variations, such an auto-levelling mechanismcan be constructed in a :much simpler and less expensive manner, as itneed merely level out short term variations.

It is a further very important advantage of the invention that thecontrol mechanism can be built into existing plants with only minormachine adaptations.

What is claimed is:

l. A method of producing an even continuous arrangement of fibers from acontinuous stream of individualized flocks of fibers comprising thesteps of guiding the stream into a chute,

depositing the flocks in the stream in the chute to form a fiber flockcolumn,

draining the air in the stream from the chute above the fiber flockcolumn,

maintaining a constant free air escape zone for the draining of the air,

providing a lower pressure at the lower end of the fiber flock column tocreate an air pressure drop applied to the fiber flock column forcondensing the column,

removing the fiber material from the fiber flock column in the chute inthe form of a continuous fiber arrangement;

measuring the fiber arrangement removed from the chute to determine adeviation of the mass of the arrangement from a preset mass; and

changing the pressure drop in correspondence to the occurrence of adeviation of the mass of the arrangement from the present mass to obtainan even continuous fiber arrangement from the chute.

2. In a method of producing an even continuous arrangement of fibers thesteps of forming a fiber flock column,

subjecting the fiber flock column to an air pressure differentiallongitudinally of the column for condensing the fiber material in thecolumn,

removing a fiber layer from the column,

measuring a characteristic of the mass of the removed fiber layer,

comparing the measured characteristic of the fiber layer with a presetvalue to determine a deviation therefrom, and

changing the pressure differential on the column in response to theoccurrence of a deviation of the measured characteristic from the presetvalue to eliminate the occurrence of a subsequent deviation.

3. A method of producing an even continuous fiber arrangement from acontinuous stream of individual ized fiber flocks comprising the stepsof depositing at least a portion of the fibers of the continuous streaminto a chute to form a fiber flock column therein,

subjecting the fiber flock column to a lower pressure at the lowerportion thereofthan on the upper end thereof to create an air pressuredrop to which the fiber flock column is subjected for condensing thefiber flock column,

removing the fiber material from the fiber flock column in the chute inthe form of a continuous fiber arrangement;

measuring the continuous fiber arrangement to determine a deviation ofthe mass of the arrange ment from a preset mass; and

changing the air pressure drop in response to the occurrence ofadeviation of the mass of the continuous fiber arrangement from thepreset mass.

4. A method of producing an even continuous fiber arrangement from astream of individualized fiber flocks comprising the steps of depositingat least a portion of the fibers of the stream into a chute to form afiber flock column therein; subjecting the fiber flock column to a lowerair pressure at the lower portion thereof than on the upper end thereofto create an air pressure drop to which the fiber flock column issubjected for condensing the fiber flock column; removing the fibermaterial from the fiber flock column at the lower end of the chute inthe form of a continuous fiber arrangement;

measuring the mass of the fiber adjacent to the lower end of the chuteto determine a deviation of the mass from a preset mass; and

changing the air pressure drop in response to the occurrence of adeviation of the mass of the fiber from the preset mass.

5. A method of producing an even continous fiber arrangement from acontinuous stream of individualized fiber flocks comprising the steps ofdepositing at least a portion of the fibers of the continuous streaminto a chute to form a fiber flock column therein,

subjecting the fiber flock column to a lower pressure at the lowerportion thereof than on the upper end thereof to create an air pressuredrop to which the fiber flock column is subjected for condensing thefiber flock column,

removing the fiber material from the fiber flock column in the chute inthe form of a continuous fiber arrangement;

measuring the fiber arrangement downstream of the chute to determine adeviation of the mass of the arrangement from a preset mass; and

changing the pressure drop in response to the occurrence of a deviationof the mass of the arrangement from the preset mass to obtain an evencontinuous fiber arrangement from the chute.

6. A method as set forth in claim 5 wherein a fan is connected incommunication with the chute to generate the pressure at the upper endthereof and wherein the rotating speed of the fan is varied to effectthe change in pressure drop.

7. A method as set forth in claim 5 wherein the fiber arrangement ismeasured upon leaving the chute,

8. A method as set forth in claim 5 wherein a plurality of chutes have afiber flock column formed therein and removed therefrom in the form of acontinuous fiber arrangement and wherein the fiber arrangements are eachmeasured and an average value measurement is determined, said averagevalue measurement being used to obtain a deviation from the preset mass.

9. A method as set forth in claim 5 wherein the chute is connected to :1transporting duct to receive at least a portion of the stream ofindividualized fibers therefrom, and wherein the pressure in thetransporting duct is changed to vary the pressure drop applied to thefiber flock column in the chute to adjust the condensation of the columnto the preset mass.

10. A method as set forth in claim 9 wherein the cross-sectional flowarea of the duct is varied to obtain a change in pressure.

11. An apparatus for producing an even continuous fiber arrangement froma stream of individualized fiber flocks comprising an air transportingduct for conveying the stream of individualized fiber flocks;

feed chute connected to said duct for a formation of a fiber flockcolumn therein from the stream, said chute and said duct being disposedto subject the fiber flock column in said chute to a pressure droplongitudinally of the column, and said chute having a perforated wallfor draining of the air from the stream entering into said chute;

a level control device disposed in the region of said perforated wallfor controlling the quantity of fiber flocks supplied to said chute tomaintain a constant fiber flock column height therein;

means for varying the air pressure in said chute; and

a measuring device disposed in the path of a fiber arrangement removedfrom said chute for measuring a characteristic of the mass of theremoved arrangement, said measuring device being connected to saidpressure varying means for controlling said pressure varying means inresponse to a measured characteristic deviating from a preset value tocause said pressure varying means to change the pressure in said chutefor elimination of subsequent deviations.

12. An apparatus for producing an even continuous fiber arrangement froma continuous stream of in dividualized fiber flocks comprising an airtransporting duct for conveying the continuous stream ofindividualizedfiber flocks;

at least one feed chute connected to said transporting duct for aformation of a fiber flock column therein from the continuous stream,said chute and duct being disposed to subject the fiber flock column insaid chute to an air pressure drop lon gitudinally ofthe column;

means for varying the air pressure drop in said chute;

and

a measuring device disposed in the path of the fiber arrangementdownstream of said chute for measuring a characteristic of the mass ofthe arrangement, said measuring device being connected to said pressurevarying means to control said pressure varying means in response to ameasured characteristic deviating from a preset value to cause saidmeans to change the air pressure drop in said chute for elimination ofsubsequent deviations.

13. An apparatus as set forth in claim 12 which further comprisestake-off rolls at the end of said chute for removing the fiberarrangement and wherein said measuring device is positioned on saidtake-off rolls.

14. An apparatus as set forth in claim 12 wherein said means includes afan of variable rotational speed arranged upstream of said chute, therotational speed of said fan being varied in response to a measureddeviation.

15. An apparatus as set forth in claim 14 wherein said fan is disposedwithin said duct.

16. An apparatus as set forth in claim 12 wherein said means is mountedin said duct downstream of said chute for varying the cross-sectionalflow area of said duct thereat in response to a measured deviation tovary7the pressure in said duct.

l An apparatus as set forth in claim 16 wherein said means is a movablymounted baffle.

18. An apparatus as set forth in claim 12 which further comprises amachine for receiving the removed fiber arrangement including a feedroller for conveying the fiber arrangement therein and wherein saidmeasuring device is mounted on said feed roll.

19. An apparatus as set forth in claim 18 wherein said machine is acard.

20. An apparatus as set forth in claim 12 which further comprises amachine for receiving the removed fiber arrangement and wherein saidmeasuring device is mounted downstream of said machine on a deliveryside thereof.

2]. An apparatus as set forth in claim 20 wherein said machine is acard.

22. An apparatus as set forth in claim [2 wherein said measuring deviceincludes a control loop comprising a pneumatic measuring device, apneumatic control device connected to said pneumatic measur ing deviceand a piston connected to and between said control device and saidpressure varying means for controlling said pressure varying means inresponse to actuation of said control device.

1. A method of producing an even continuous arrangement of fibers from acontinuous stream of individualized flocks of fibers comprising thesteps of guiding the stream into a chute, depositing the flocks in thestream in the chute to form a fiber flock column, draining the air inthe stream from the chute above the fiber flock column, maintaining aconstant free air escape zone for the draining of the air, providing alower pressure at the lower end of the fiber flock column to create anair pressurE drop applied to the fiber flock column for condensing thecolumn, removing the fiber material from the fiber flock column in thechute in the form of a continuous fiber arrangement; measuring the fiberarrangement removed from the chute to determine a deviation of the massof the arrangement from a preset mass; and changing the pressure drop incorrespondence to the occurrence of a deviation of the mass of thearrangement from the present mass to obtain an even continuous fiberarrangement from the chute.
 2. In a method of producing an evencontinuous arrangement of fibers the steps of forming a fiber flockcolumn, subjecting the fiber flock column to an air pressuredifferential longitudinally of the column for condensing the fibermaterial in the column, removing a fiber layer from the column,measuring a characteristic of the mass of the removed fiber layer,comparing the measured characteristic of the fiber layer with a presetvalue to determine a deviation therefrom, and changing the pressuredifferential on the column in response to the occurrence of a deviationof the measured characteristic from the preset value to eliminate theoccurrence of a subsequent deviation.
 3. A method of producing an evencontinuous fiber arrangement from a continuous stream of individualizedfiber flocks comprising the steps of depositing at least a portion ofthe fibers of the continuous stream into a chute to form a fiber flockcolumn therein, subjecting the fiber flock column to a lower pressure atthe lower portion thereof than on the upper end thereof to create an airpressure drop to which the fiber flock column is subjected forcondensing the fiber flock column, removing the fiber material from thefiber flock column in the chute in the form of a continuous fiberarrangement; measuring the continuous fiber arrangement to determine adeviation of the mass of the arrangement from a preset mass; andchanging the air pressure drop in response to the occurrence of adeviation of the mass of the continuous fiber arrangement from thepreset mass.
 4. A method of producing an even continuous fiberarrangement from a stream of individualized fiber flocks comprising thesteps of depositing at least a portion of the fibers of the stream intoa chute to form a fiber flock column therein; subjecting the fiber flockcolumn to a lower air pressure at the lower portion thereof than on theupper end thereof to create an air pressure drop to which the fiberflock column is subjected for condensing the fiber flock column;removing the fiber material from the fiber flock column at the lower endof the chute in the form of a continuous fiber arrangement; measuringthe mass of the fiber adjacent to the lower end of the chute todetermine a deviation of the mass from a preset mass; and changing theair pressure drop in response to the occurrence of a deviation of themass of the fiber from the preset mass.
 5. A method of producing an evencontinous fiber arrangement from a continuous stream of individualizedfiber flocks comprising the steps of depositing at least a portion ofthe fibers of the continuous stream into a chute to form a fiber flockcolumn therein, subjecting the fiber flock column to a lower pressure atthe lower portion thereof than on the upper end thereof to create an airpressure drop to which the fiber flock column is subjected forcondensing the fiber flock column, removing the fiber material from thefiber flock column in the chute in the form of a continuous fiberarrangement; measuring the fiber arrangement downstream of the chute todetermine a deviation of the mass of the arrangement from a preset mass;and changing the pressure drop in response to the occurrence of adeviation of the mass of the arrangement from the preset mass to obtainan even continuous fiber arrangement from the chute.
 6. A method as setforth in claim 5 wherein a fan is conNected in communication with thechute to generate the pressure at the upper end thereof and wherein therotating speed of the fan is varied to effect the change in pressuredrop.
 7. A method as set forth in claim 5 wherein the fiber arrangementis measured upon leaving the chute.
 8. A method as set forth in claim 5wherein a plurality of chutes have a fiber flock column formed thereinand removed therefrom in the form of a continuous fiber arrangement andwherein the fiber arrangements are each measured and an average valuemeasurement is determined, said average value measurement being used toobtain a deviation from the preset mass.
 9. A method as set forth inclaim 5 wherein the chute is connected to a transporting duct to receiveat least a portion of the stream of individualized fibers therefrom, andwherein the pressure in the transporting duct is changed to vary thepressure drop applied to the fiber flock column in the chute to adjustthe condensation of the column to the preset mass.
 10. A method as setforth in claim 9 wherein the cross-sectional flow area of the duct isvaried to obtain a change in pressure.
 11. An apparatus for producing aneven continuous fiber arrangement from a stream of individualized fiberflocks comprising an air transporting duct for conveying the stream ofindividualized fiber flocks; a feed chute connected to said duct for aformation of a fiber flock column therein from the stream, said chuteand said duct being disposed to subject the fiber flock column in saidchute to a pressure drop longitudinally of the column, and said chutehaving a perforated wall for draining of the air from the streamentering into said chute; a level control device disposed in the regionof said perforated wall for controlling the quantity of fiber flockssupplied to said chute to maintain a constant fiber flock column heighttherein; means for varying the air pressure in said chute; and ameasuring device disposed in the path of a fiber arrangement removedfrom said chute for measuring a characteristic of the mass of theremoved arrangement, said measuring device being connected to saidpressure varying means for controlling said pressure varying means inresponse to a measured characteristic deviating from a preset value tocause said pressure varying means to change the pressure in said chutefor elimination of subsequent deviations.
 12. An apparatus for producingan even continuous fiber arrangement from a continuous stream ofindividualized fiber flocks comprising an air transporting duct forconveying the continuous stream of individualized fiber flocks; at leastone feed chute connected to said transporting duct for a formation of afiber flock column therein from the continuous stream, said chute andduct being disposed to subject the fiber flock column in said chute toan air pressure drop longitudinally of the column; means for varying theair pressure drop in said chute; and a measuring device disposed in thepath of the fiber arrangement downstream of said chute for measuring acharacteristic of the mass of the arrangement, said measuring devicebeing connected to said pressure varying means to control said pressurevarying means in response to a measured characteristic deviating from apreset value to cause said means to change the air pressure drop in saidchute for elimination of subsequent deviations.
 13. An apparatus as setforth in claim 12 which further comprises take-off rolls at the end ofsaid chute for removing the fiber arrangement and wherein said measuringdevice is positioned on said take-off rolls.
 14. An apparatus as setforth in claim 12 wherein said means includes a fan of variablerotational speed arranged upstream of said chute, the rotational speedof said fan being varied in response to a measured deviation.
 15. Anapparatus as set forth in claim 14 wherein said fan is disposed withinsaid duct.
 16. An apparatus as set forth in claim 12 whereiN said meansis mounted in said duct downstream of said chute for varying thecross-sectional flow area of said duct thereat in response to a measureddeviation to vary the pressure in said duct.
 17. An apparatus as setforth in claim 16 wherein said means is a movably mounted baffle.
 18. Anapparatus as set forth in claim 12 which further comprises a machine forreceiving the removed fiber arrangement including a feed roller forconveying the fiber arrangement therein and wherein said measuringdevice is mounted on said feed roll.
 19. An apparatus as set forth inclaim 18 wherein said machine is a card.
 20. An apparatus as set forthin claim 12 which further comprises a machine for receiving the removedfiber arrangement and wherein said measuring device is mounteddownstream of said machine on a delivery side thereof.
 21. An apparatusas set forth in claim 20 wherein said machine is a card.
 22. Anapparatus as set forth in claim 12 wherein said measuring deviceincludes a control loop comprising a pneumatic measuring device, apneumatic control device connected to said pneumatic measuring deviceand a piston connected to and between said control device and saidpressure varying means for controlling said pressure varying means inresponse to actuation of said control device.